This invention relates to a display unit. More particularly the invention is concerned with a display unit of the kind in which a blind printed with display material is windable between a pair of rollers for presenting a selected area of the blind for display in a frame or window area.
Roller blind displays have been widely used for many purposes including advertising and presentation of information. In such displays a blind carries a sequence of displays along its length. It is wound between a pair of parallel spaced rollers through a display window area, the blind being wound off one roller onto the other. Various controllable drive mechanisms have been used conventionally driven by an electric motor. Such drive mechanisms including indexing means to halt the drive when a selected portion of the blind is in the display window area. The present invention seeks to provide a drive mechanism which is reliable and easy to use and, in particular, one which can be manually actuated.
The present invention is applied to a display apparatus of the kind comprising first and second rollers rotatably mounted in spaced parallel relationship for winding a blind carried by the rollers therebetween through a display area to locate a selected portion of the blind thereat; and drive means for rotating one or other roller to cause lengthwise movement of the blind.
In accordance with the present invention in display apparatus of the above kind, the drive means comprises first and second drive portions rotatable with said first and second rollers respectively, said first and second drive portions being located at opposite sides of the rollers as seen from the display area.
A flexible elongate drive element is terminated at one end at the first drive portion, and is wound in a plurality of turns about the first drive portion. The drive element is terminated at the other end at the second drive portion and is wound in a plurality of turns about the second drive portion so as to be wound thereon when the drive element is wound off the first drive portion and vice versa. The drive element has an intermediate section-supported for lengthwise movement thereof in a predetermined path between the turns wound on the first and second portions and the predetermined path includes a portion at which the intermediate section is manually actuable to apply a drive force to one or other of the rollers.
The blind carried by the rollers may be a carrier for graphics, e.g. a printed display blind attached to the carrier blind. The carrier blind acts to transmit drive from the roller to which drive is applied to wind the carrier thereon to the other roller from which the blind is being wound off. The display apparatus may be constructed in the form of a light box in which the carrier blind is back lit. To this end the carrier blind is made light transmissive.
In a preferred embodiment of the display apparatus of the invention the above-mentioned portion of the predetermined path is substantially parallel to and in the plane of said first and second rollers outside the space between the rollers occupied by the blind. More particularly the rollers are supported in a rectangular housing parallel to and adjacent respective ones of two opposed sides thereof and the portion of the predetermined path lies external to one of said two opposed sides to be manually accessible. One of these two opposed sides contains first and second apertures through which the flexible element extends to the external portion of the predetermined path. Manually-engageable (e.g. graspable) means is carried by the flexible element at the external portion of said predetermined path.
The manually-engageable means is sized to be unable to pass through the apertures and thereby limits the extent of movement of the manually-engageable means. Preferably the manually-engageable means is a spring-loaded device acting to maintain tension on the flexible element. In the preferred embodiment of the invention the flexible element extends from the first drive portion in a direction past the second roller and extends from said second drive portion to engage a part acting as a guide pulley rotatable with the first drive roller and return towards and past the second drive portion.
Furthermore in the preferred embodiment of the display apparatus the ratio of the diameter of each of the first and second rollers to the diameter of each of the first and second drive portions respectively is such that a movement of the flexible element through a distance between said apertures causes the blind to be wound over a length that is at least twice the dimension of said display area in the lengthwise direction of the blind.